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Saddle-case Maker Genus Glossosoma (Little Brown Short-horned Sedges)

Taxonomic Navigation -?-
» Genus Glossosoma (Little Brown Short-horned Sedges)
Species in GlossosomaNumber of SpecimensNumber of Pictures
Glossosoma alascense00
Glossosoma califica00
Glossosoma intermedium00
Glossosoma lividum00
Glossosoma montana00
Glossosoma nigrior00
Glossosoma penitum00
Glossosoma traviatum00
Glossosoma velona00

13 species aren't included.
Common Names
Pictures Below
The sporadic emergence of these caddisflies diminishes the importance of the freshly emerged adults and pupae, but they have unique periods of vulnerability as larvae during the day and again as diving egg layers at dusk that can make them very important. A taxon can only have one common name attached in the title but this is one of those genera whose species come in a variety of colors and descriptive common names. In the West their bodies generally come in tan to brown shades with matching wings, their wings can be speckled grayish tan or even almost black as with an eastern species. Some western rivers have astounding populations. See Glossosomatidae for more information.  

Where & When

Regions: East, Midwest, West

Time Of Year (?): Early Summer

Preferred Waters: Riffle sections

Hatching Behavior

Time Of Day (?): variable and sporadic

The pupae emerge on the surface, or by rising to the surface and then swimming to shore. The generally tend to trickle off all day in numbers too few to attract much interest or notice from either angler or trout.

Egg-Laying Behavior

Time Of Day: evenings, often at last light

Females dive underwater to oviposit. They can swarm in tremendous numbers, often mixed with several species.

Larva & Pupa Biology

Current Speed: Fast, for most species

Shelter Type: Rocks, shaped kind of like a turtle shell
Because Glossosoma cases are built to a fixed size, the larvae have to abandon them and build new ones as they grow. In the process they often accidentally or deliberately end up drifting downstream for awhile. They synchronize this activity as tightly as most species synchronize emergence, prompting trout to feed selectively on the larvae. Even better news for the angler is this activity is diurnal. Unfortunately, the timing is not predictable and while generally a morning occurrence, it can happen any time of day. A further handicap is that the behavioral drift (Behavioral drift: The nymphs and larvae of many aquatic insects sometimes release their grip on the bottom and drift downstream for a while with synchronized timing. This phenomenon increases their vulnerability to trout just like emergence, but it is invisible to the angler above the surface. In many species it occurs daily, most often just after dusk or just before dawn.) is not visible. The angler will only know it's happening by periodically seining the drift or fishing proper imitations until the fish start to respond.

This usually occurs several times during their development in the spring and summer. In Caddisflies, LaFontaine recommends imitating the naked pinkish-colored larvae drifting without their cases. They also come in shades of pale tan or yellow.

Pictures of 2 Saddle-case Maker Specimens in the Genus Glossosoma:

Male Glossosoma alascense Saddle-case Maker AdultMale Glossosoma alascense  Saddle-case Maker Adult View 8 PicturesI lost track of this specimen before I could get it under my microscope, but caddis expert Dave Ruiter was able to identify it from pictures as Glossosoma, with an uncertain suggestion of G. alascense as the most likely species.
Collected July 9, 2019 from Rock Creek in Montana
Added to by Troutnut on July 18, 2019

2 Underwater Pictures of Glossosoma Saddle-case Makers:

Three big Ephemerella subvaria mayfly nymphs share a rock with some cased caddis larvae.  In this picture: Mayfly Species Ephemerella subvaria (Hendrickson) and Saddle-case Maker Genus Glossosoma (Little Brown Short-horned Sedges). From the Namekagon River in Wisconsin.
Date TakenMar 20, 2004
Date AddedJan 25, 2006
In this picture: Saddle-case Maker Genus Glossosoma (Little Brown Short-horned Sedges). From the East Branch of Trout Brook in New York.
Date TakenSep 20, 2006
Date AddedOct 4, 2006
CameraPENTAX Optio WPi

Recent Discussions of Glossosoma

Glossosoma intermedium or nigrior 5 Replies »
Posted by Wiflyfisher on Jun 30, 2020
Last reply on Jul 31, 2020 by Creno
Caught and photographed in the Upper Midwest on May 12, 2020. I resized my original photo for the website.

(User-posted images are only viewable in the forum section.)

Replypupa color 7 Replies »
Posted by LittleJ on Apr 19, 2008
Last reply on Apr 22, 2008 by LittleJ
I was thinking very dark olive w/a ginger shuck. Sound right to any of you?
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